The invention relates to an improvement to a commercially available sport card slitting machine known as the "Rollem Slip Stream" machine, and more particularly to an improved first stage slitting assembly therefor.
Sport cards, such as baseball trading cards and the like, are very popular. Several major companies, including the present assignee, compete vigorously in this large market.
In the manufacture of sport cards, a large number of photographs of various individual athletes are printed on each of many large, single sheets of suitable paper (herein referred to as "photo sheets". The large photo sheets then are slit, first "horizontally" and then "vertically" to form a group or collection of individual sport cards which then are collated and packaged.
To this end, the sport card industry has used a card slitting machine called the "Rollem Slip Stream Machine". The "standard" Rollem Slip Stream machine includes a first stage slitting assembly that is manufactured by Rollem, and is shown in FIG. 1. Various aspects of the Rollem Slip Stream machine are disclosed in U.S. Pat. No. 4,405,121 by Hill, issued Sep. 20, 1983 entitled "Cutting and Collating Sheets of Paper Cards, etc.", and incorporated herein by reference.
FIG. 1 herein shows a top view diagram of the Rollem Slip Stream machine. A large (typically 28 inches by 40 inches) sheet of photographs is advanced by a sheet feeder 24 (FIG. 4) along a first section 11, as indicated by arrow 13. A first stage slitting assembly 15 includes a lower blade assembly 40 and an upper blade assembly 30, as shown in FIG. 3. The prior art Rollem first stage slitting assembly makes "interrupted cut" slits such as 21 in a photo sheet 20, as shown in FIG. 2. The "interrupted cut" slits 21 are necessary so that photo sheet 20 remains intact to allow it to be advanced as a unit first in direction 16 (FIG. 1) and then at a right angle in direction 17 to a second stage slitting assembly 18 into a second section 12, after the "horizontal" interrupted cut slits 21 are made. More specifically, in first stage slitting assembly 11, thirteen individual "interrupted cut" slits 21 are made, each of which extends to within approximately 1/2 inch of the opposed leading and trailing edges 20A and 20B (FIG. 2) of sheet 20, leaving edge margins 22A and 22B that maintain horizontally slit photo sheet 20 intact so further handling of the entire sheet is possible. The second stage slitting assembly 18 cuts a second set of "vertical" slits (not shown) that are perpendicular to the "horizontal" interrupted cut slits 21.
Referring to FIG. 3, the prior art Rollem Slip Stream first stage slitting assembly 15 includes thirteen upper hub/blade assemblies 30 mounted on a single-gear driven shaft 10. Each hub/blade assembly 30 includes a disk-shaped upper blade 30A secured by set screws (not shown) to a planar face of an upper hub 30B. Several set screws (not shown) secure the various hubs 30B to shaft 10, which is journaled in several stationary bearing assemblies (not shown).
Numeral 40 designates lower hub/blade assemblies of the standard Rollem first stage slitting assembly 15. Each lower hub/blade assembly 40 includes a blade 40A mounted on a hub 40B which in turn is mounted on a common shaft 41. Shaft 41 is gear driven and "synchronized" with the drive of the upper shaft 10 so that the cutting edge velocity of upper blade 30A is precisely the same as that of lower blade 40A. The lower blades 40A are of larger diameter than the upper blades 30A.
To produce the above-mentioned "interrupted cut" slits 21, lower blades 40A each have two spaced notches 40C-1 and 40C-2, as shown in 20 FIG. 4. The feeding of photo sheet 20 is synchronized to the times at which trailing edge 42A of notch 40C-1 and leading edge 42B of notch 40C-2 meet the upper blade 30A to produce the leading half inch margin 22A and the trailing half inch margin 22B (FIGS. 2 and 2A) that keep photo sheet 20 intact after the horizontal "interrupted cut" slits 21 are made.
The above-described prior art Rollem first stage slitting assembly 15 has several serious shortcomings, caused by the facts that (1) upper blades 30A all are very rigidly connected together by common shaft 10 and all of the lower blades 40A also are rigidly connected together by common shaft 41, (2) the lateral forces 52 (FIG. 3) with which the upper blades 30A abut the lower blades 40A is critical to the quality of the cuts, and (3) it is very difficult to adjust the individual positions of all thirteen of the upper hubs 30B supporting blades 30A on upper shaft 10 so that the lateral forces 52 of each upper blade 30A against the corresponding lower blade 40A are uniform, especially if either an upper blade 30A or a lower blade 40A happens to be slightly warped or non-uniformly worn.
Non-uniform lateral blade abutment forces 52 result in both excessive, irregular blade wear and ragged "interrupted cut" slits 21. In practice, operation of the Rollem Slip Stream machine often must be halted to allow (1) adjustment of the lateral blade abutment forces 52, and (2) various blade and maintenance/replacement operations. Such efforts and the resulting "down time" of the Rollem Slip Stream machine often interrupt production of sport cards for many hours. Efforts to "quick fix" a machine making slits 21 less ragged by adjusting a blade to increase the lateral blade abutment forces 52 often results in overheating of the blade edges and loss of temper thereof.
Consequently, for many years there has been an unmet need for a practical, economical solution to the above shortcomings of the Rollem Slip Stream sport card slitting machines even though such shortcomings were generally accepted as unavoidable.